What a Retatrutide dose actually costs

Why milligram price is the wrong number

Retatrutide is sold by the vial, in 5, 10, 15, 20 and 30 mg sizes. The obvious way to compare them is price divided by milligrams. That number is misleading, because you do not consume milligrams. You consume doses, and a dose is a fixed amount pulled from a vial that may not contain a whole multiple of it.

The useful figure is price divided by the number of whole doses the vial yields. Anything left over after the last whole dose is product you paid for and cannot use as a dose. On this page that leftover is called stranded.

The table above runs that division at a 4 mg dose across every vial size sold. It reports whole doses, stranded milligrams, and stranded milligrams as a percentage of the vial. To get your own cost per dose, divide the vial price by the whole doses column, not by the vial size.

What the table shows at a 4 mg dose

Three things stand out. The first is that the 20 mg vial divides cleanly. It yields 5 whole doses and strands nothing. Every milligram you pay for becomes part of a dose, so the cost per dose is exactly the vial price divided by five.

The second is that the 5, 10 and 15 mg vials all strand the same proportion, 20 percent, even though the absolute stranded amount grows from 1 mg to 3 mg. This is arithmetic, not coincidence. Each of those sizes is a multiple of 5, and 4 divides into 5 leaving a fifth of it behind every time. Buying a larger vial from that group does not improve your waste rate at all. It only scales the same inefficiency up.

The third is the 30 mg vial, which sits between the two. It yields 7 whole doses and strands 2 mg, or 6.7 percent. Better than the multiples of 5, worse than the clean 20 mg. If two vials carry the same price per milligram, the 20 mg is the cheaper one per dose, and the 30 mg is second.

The stranded amount is real, not theoretical

Stranded product is not measurement error or residue in the syringe. It is a quantity that exists in the vial and is simply smaller than one dose. A 5 mg vial at a 4 mg dose leaves 1 mg sitting in solution after the first draw.

Whether that leftover has any use is not a question this page answers. Combining remnants across vials, saving them, or adjusting a dose to use them up are all decisions with clinical and sterility dimensions, and there is no medical review behind this site. What the arithmetic can tell you is only how much is left and what fraction of your purchase it represents.

If you plan to treat the leftover as waste, price the vial against the whole doses column and ignore the stranded milligrams entirely. That is the conservative reading and the one that makes vial sizes comparable to each other.

Reconstitution volume does not change the arithmetic

Retatrutide vials are reconstituted with bacteriostatic water, and listings use volumes of 1, 2, 2.5 and 3 mL. The water volume changes the concentration and therefore how many syringe units make up a dose. It does not change how many milligrams are in the vial, so it does not change how many whole doses the vial yields or how much is stranded.

This matters because a common assumption is that adding more water gets more out of a vial. It does not. A 15 mg vial contains 15 mg whether it is dissolved in 1 mL or 3 mL. At a 4 mg dose it yields 3 whole doses either way, and strands 3 mg either way. Volume only affects the number on the syringe barrel.

What volume does affect is measurement practicality. Too concentrated and a dose becomes a very small mark to read. Too dilute and a dose may exceed the syringe capacity. Those are handling constraints, separate from cost.

Retatrutide, code LY3437943, is not approved by any regulator for human use. This page does the division and nothing else.

What we do not know

Retatrutide is modelled end to end on this site: half life, absorption, accumulation and clearance are all computed.

This page answers arithmetic and handling questions. It does not tell you what dose to take, what to expect, or whether anything is appropriate for you, and there is no medical review behind it.

Common questions

Which Retatrutide vial size is cheapest per dose?

At a 4 mg dose, the 20 mg vial is the most efficient of those listed, yielding 5 whole doses with nothing stranded. That is efficiency of use, not price. If a supplier charges more per milligram for the 20 mg vial, the arithmetic advantage can be cancelled out. Compare vial price divided by whole doses, using your own prices.

Why do the 5, 10 and 15 mg vials all waste 20 percent?

Because each is a multiple of 5, and a 4 mg dose leaves a fifth of every 5 mg behind. The absolute stranded amount rises from 1 mg to 3 mg as the vial grows, but the proportion stays fixed. Stepping up within that group does not reduce the waste rate.

Does adding more bacteriostatic water get more doses out of a vial?

No. Water volume sets concentration, not content. A vial holds the same milligrams at 1 mL as it does at 3 mL, so the whole doses and stranded amounts in the table are unchanged. Volume only changes how many units on the syringe correspond to a dose.

What should I do with the stranded milligrams?

This page cannot answer that. Whether leftover product can be pooled, stored, or used in a partial dose involves sterility and clinical judgment, and there is no medical review behind this site. The arithmetic only reports how much is left over.

Does the table change if my dose is not 4 mg?

Yes, completely. The whole doses and stranded figures shown are computed at 4 mg only. Listings also show doses of 1, 2, 8 and 12 mg, and each produces a different division against each vial size. A 4 mg dose is used here as one worked example.

Is a smaller vial ever the better buy?

It can be, on grounds the arithmetic does not cover. Smaller vials mean less product committed at once and shorter time in solution after reconstitution. Those are handling considerations. On cost per dose alone at 4 mg, the 5, 10 and 15 mg vials all strand 20 percent.